Adds new core EEJS library file
Adds new EEDT view model class
Adds panel extension classes for all 7 native EEDT panels

 They all extend from a base panel for convenience.  Each panel class is designed to be exactly like
 a third party panel extension, in that it uses a method "ee_debug_toolbar_add_panel" to consume
 an Eedt_view_model instance that is modified with panel details such as name, button label etc
 and then returned for rendering.  Basically we're eating our own dog food. Which is good.
Renamed id attribute used in config panel view partial for consistency
Renamed db view partial to follow panel name convention
Renamed id attribute used in files panel view partial for consistency
Toolbar Extension modified to use Eedt_view_model instances for building toolbar panels

Toolbar main view script also updated to call methods on each Eedt_view_model panel instance to
retrieve html, title etc for populating the view.